This is a study of the myocardial sarcolemma and the extracellular matrix. This project attempts to gain an understanding of the function of the myocardial sarcolemma from an ultrastructural analysis of the components of the cell surface (glycocalyx) in the bilayer, their relationship to each other, to the extracellular matrix and to membrane transport. The approach is to study the macromolecular architecture of the bilayer and glycocalyx/extracellular matrix with state-of-the-are freeze-fracture and immunoelectron microscopy. The overall aims are to determine (1) if any of the intramembrane particles as revealed in freeze-fracture and freeze-etch membrane are related to ion transport and (2) which specific macromolecules within the glycocalyx have an important structural and functional relationship to the bilayer and to components of he extracellular matrix. The methodology is to (1) examine the filament of the glycocalyx and extracellular matrix to determine in untreated tissue their configuration and identity. This will be performed in normal hearts, during development and after brief periods of ischemia, (2) to determine the distribution and localization in the bilayer of two major transport proteins, i.e. Na,K- ATPase and Na-Ca exchanger. A combination of the following techniques will be used on isolated adult myocytes, cultured myocytes and heart tissue: ultra-rapid freezing, freeze-drying, freeze-substitution, low temperature embedding, freeze-fracture and etch, antibody and immunogold labeling and label fracture. The proposed research has a two-fold significance, (1) by identifying structural components of the glycocalyx/extracellular matrix and intramembrane particles int he bilayer, with specific membrane function it addresses a question fundamental to the biology of all cells and (2) it utilizes stat-of-the-art ultrastructure to focus on structure-function relationships (both physiological and pathological) of the sarcolemma and extracellular matrix, where in the heart there is little information.